During this year, we intend to pursue our work on the mechanism of activation of human plasminogen by streptokinase. We will evaluate the ability of various plasminogen species to complex wiih streptokinase, and to generate an active site in the plasminogen moieties, as a result of complex formation (in those species in which it occurs). We hope to contribute information as to the reason(s) for the insensitivity of certain species of plasminogen (e.g. sheep) to activation by streptokinase. We also will continue our studies on the circulating structure of human plasminogen. In this coming year, we hope to measure the nature and strength of the binding of 6-amino caproic acid to the various plasminogen activation intermediates. Additionally, we will isolate the subforms of the human plasminogen isozymes, and determine their carbohydrate compositions, in order to determine whether microheterogeneity in the carbohydrate moiety plays any role in the heterogeneity in structure of plasminogen in plasma.